The only thing that remains is writing language to ensure that
specifying xmlns: in non-xml mode HTML documents does not result in a
validator warning. Once that language is written, I'll ask for it to be
published as a FPWD.

HTML5 (normative semantics - externally defined)
------------------------------------------------
This document would modularize Microdata into an external specification
and incorporate both Microdata and RDFa normatively (by reference) into
the HTML5 specification.

HTML5 (non-normative semantics - externally defined)
----------------------------------------------------
This document would modularize Microdata, but would not refer to either
Microdata or RDFa normatively (by reference or by inclusion).

I plan to give each of these drafts plenty of time for feedback from the
community as well as follow-up editing.

These three drafts would allow consensus to form around the following
options:

1. Whether or not to normatively incorporate RDFa into the HTML5 spec
(by reference).
2. Whether or not to normatively incorporate Microdata into the HTML5
spec (by reference).
3. Whether or not to normatively incorporate any semantic technology
into the HTML5 spec.